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Thread: 5.7 Fuel Consumption #s

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    Member Yukoner's Avatar
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    Default 5.7 Fuel Consumption #s

    Thought this would be of interest.
    Was out on the weekend on a short Moose hunt. Crunched the numbers for fuel consumption based off hours of run time and actual fuel used.
    I was very surprised at how low my numbers were. Boat is a 20' Wooldridge Sport with a 5.7 carb and 212 pump.
    I averaged 7.5 GPH for the whole trip. Pretty reasonable I thought.
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    Member emartens123's Avatar
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    Those are very good numbers.
    What kind of weight were you packing ?
    I have a 17 ft Firefish with the 175 SJ and my fuel useage will always be around the 8-9 gph mark on average.
    That's the problem with the smaller boats,can never pack enough fuel to go any distance.
    I'm starting to think the 20 ft boats are the way to go.
    Did ya get your Moose on the trip

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    Member Yukoner's Avatar
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    Quote Originally Posted by emartens123 View Post
    Those are very good numbers.
    What kind of weight were you packing ?
    I have a 17 ft Firefish with the 175 SJ and my fuel useage will always be around the 8-9 gph mark on average.
    That's the problem with the smaller boats,can never pack enough fuel to go any distance.
    I'm starting to think the 20 ft boats are the way to go.
    Did ya get your Moose on the trip
    That was 4 people, 3 days gear, full fuel and extra (80 USG). Not a big load.
    Averaged 3000-3300 RPM with WOT at 4K RPM. If I had a Moose in there, my cruise RPM is still 3200-3300 once on step.
    No Moose this trip, but I already filled the freezer earlier. This was for fun.
    Iv'e been really happy with my fuel use as compared to my old Sport with a 150 Opti OB jet.
    Never wrestle with a pig.
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    Member emartens123's Avatar
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    Quote Originally Posted by Yukoner View Post
    That was 4 people, 3 days gear, full fuel and extra (80 USG). Not a big load.
    Averaged 3000-3300 RPM with WOT at 4K RPM. If I had a Moose in there, my cruise RPM is still 3200-3300 once on step.
    No Moose this trip, but I already filled the freezer earlier. This was for fun.
    Iv'e been really happy with my fuel use as compared to my old Sport with a 150 Opti OB jet.
    Not a big load,
    I could never pack that kind of weight with my boat.
    i need to get a bigger boat.
    Yukoner how do you like that Wooldridge for the type of rivers you have up there.I am really looking at them Wooldridge boats, the only thing I don't like is the fuel tank in the bottom of the boat.You ever think about putting a hole in the bottom and rupturing your fuel tank?

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    Member jkb's Avatar
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    That is some great fuel numbers for the weight you were hauling. If I can get 10 GPh with my 150 outboard merc jet loaded I'm thrilled.
    Life is not a journey to the grave with the intention of arriving safely in a pretty well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming-----WOW-----what a ride!
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    I get around 10g/hr with a 20ft extra plus and a 351w carb (on a good day). I run a 3 stage. 7.5 is pretty darn good. I think the wider bottom boats are better on fuel consumption. Mine is older so it does not have the 72" bottom. I had two guys and gear plus 210 gal of gas going down the yukon on step at 3500 rpm (just out of the secondaries) at about 32mph. I can haul all I want with the current set-up, but a wider boat would get er done with less hull speed to keep me on step. Not worth the extra $$ to get a new boat though.

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    I have a flowscan and average 8-12 gph depending on load in my 21' Hewescraft with 351W. I usually cruise at 3200 rpm and 28mph.
    "I'd rather be fishing!"

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    Sounds about right, I have a 16' x 7' custom boat with an injected 4.3L 230hp and a Berk jet. I just finished a trip with 1,500 pounds of gear in the boat and was burning 6.2gph at 3000-3200rpm cruising avg. 33mph.

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    Member Yukoner's Avatar
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    Quote Originally Posted by emartens123 View Post
    Not a big load,
    I could never pack that kind of weight with my boat.
    i need to get a bigger boat.
    Yukoner how do you like that Wooldridge for the type of rivers you have up there.I am really looking at them Wooldridge boats, the only thing I don't like is the fuel tank in the bottom of the boat.You ever think about putting a hole in the bottom and rupturing your fuel tank?
    Honestly, I don't really worry about the rock thing. I'm not into those kind of rivers, although I could see it being a concern if I was running the Tuchodi and that sort of thing. Glen will build whatever you want though, and a doubler under the tank with UHMW might be worth it.
    Boats are spendy enough without worrying about running over rocks all day.
    I put this chart together to illustrate fuel burn between the 5.7 FI/212 combo and a 150 Optimax OB jet.
    No point including MPG, as the data was off different hulls, although fuel burn at a specific RPM will be correct regardless of hull, just MPH and thus MPG will change.
    If you look at the data, I'm cruising at 3200 with a load in my 5.7 Sport where I would have needed to be at 4500-4600 with the 150 Opti Sport. Same hull. Keep in mind the 5.7 data shown is from a FI Kodiak, and mine is carbed, regardless, my numbers seem to be very very close. Not sure why that is. Glen had mentioned the carbed is usually within 1-2 GPH.
    With 4 adults, tons of gear and fuel, I would take it up to 46-4800 to get on step quick, then back off to 32-3300 for cruising.
    Same load in the 20' Sport with a 150 Opti would be hammer the Opti WOT and wait for it to step. Then back off to 46-4700.
    So for load carrying, no question the V-8/212 combo is the way to go.
    Where the OB jet did well, but not much better, was running very light. Only maybe 1 or so GPH better than the V-8. Running light up river scouting with the V-8, I'm cruising at 2800-3000 RPM, and the Opti would be 3800-4000. In all cases, I'm going faster than the OB jet, so theoretically better MPG.
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    Never wrestle with a pig.
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    Member Akgramps's Avatar
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    Quote Originally Posted by emartens123 View Post
    Not a big load,
    I could never pack that kind of weight with my boat.
    i need to get a bigger boat.
    Yukoner how do you like that Wooldridge for the type of rivers you have up there.I am really looking at them Wooldridge boats, the only thing I don't like is the fuel tank in the bottom of the boat.You ever think about putting a hole in the bottom and rupturing your fuel tank?
    Under the floor is where the tank belongs IMO.....I have side tanks in my current boat and even though they are shaped to fit around the side trays and only 3" wide at the the bottom.....they are still in the way, a few inches doesnt seem like a big deal but its right where you want/ need to put your feet. And my wife always end up with some bruises on the shins from the top of the tanks.

    I realize there are other locations besides the sides but under the floor makes the most sense. The weight is down low and there is some structure between the bottom of the boat and the bottom of the tank. If you hit hard enough to damage the tank you are in a serious world of hurt anyway..
    “Nothing worth doing is easy”
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